Functional characterization of a chronic cyclophosphamide-induced overactive bladder model in mice

To describe a new mouse model of overactive bladder (OAB) at the histological level, pain, voiding behavior, and urodynamics, while assessing the physiological state of mice.

This paper compares the pathophysiological features of mice that received intraperitoneal injections of cyclophosphamide (CYP) (40 and 80  mg/kg - body weight) every 2 days for 7 days. Specifically, the heart rate, the body temperature, and the general activity were assessed by telemetry. The abdominal sensitivity was determined with Von Frey filaments. Voiding behavior and detrusor activity were respectively quantified by urine spotting experiments and cystometry. Hematoxylin & Eosin staining was performed to detect inflammation in tissue and NGF concentration in urine was quantified.

Affected mice exhibit clearly an OAB characterized by an increase in the number of voiding events and an urodynamically-demonstrated detrusor overactivity associated with referred hyperalgesia. The injected mice displayed inflamed bladder, urothelial hyperplasia, and increased NGF concentration in urine in dose dependant manner. However, the physiological features of mice with CYP-induced cystitis are not changed.

We can show that this model of chronic OAB with pain in mice fits more closely to the clinical signs of patients with OAB than the available animal models (acute and chronic) and will therefore be useful to highlight potential drug targets in genetically modified mice in the future.